1. Field of the Invention
The present invention relates to a hydraulic system for a forklift, which supplies hydraulic fluid to a power steering cylinder to steer wheels.
2. Description of the Related Art
A hydraulic system for a forklift is known, in which when a handle is rotatively operated, hydraulic fluid is supplied by a hydraulic pump to a power steering cylinder to steer wheels. Such a conventional hydraulic system has a torque sensor which outputs a signal corresponding to rotational torque when the handle is rotatively operated, a handle angle sensor which outputs a signal corresponding to a handle rotation angle, and a wheel angle sensor which outputs a signal corresponding to a steering angle of the wheels. The hydraulic fluid of a flow rate based on the signal from the torque sensor is discharged from the hydraulic pump to effect the power steering while a solenoid valve is driven based on the signals from the handle angle sensor and the wheel angle sensor to control the steering angle of the wheels in conformity with the handle angle.
The conventional hydraulic system for the forklift suffers from a complicated and expensive sensor mechanism in the handle portion since the torque sensor for outputting the signal corresponding to the rotational torque on the handle and the handle angle sensor for outputting the signal corresponding to the handle rotation angle must be installed on the handle portion.